Evolutionary Forces on personality Sociobiology = the study of biological bases of social behavior **psychological qualities have been retained in people over many years because they are adaptive 3 important points: 1.Reproductive success 2.Adaptive value pertains to early life 3.Adaptive value in terms of specific tasks in specific situations

What psychological mechanisms have evolved? Male/female mate preferences Females will have stronger preferencesFemales will have stronger preferences Females focus on mates’ ability to provide resourcesFemales focus on mates’ ability to provide resources Males focus on reproductive potentialMales focus on reproductive potential Sex objects vs. success objects

Evolutionary theory and attraction Genetic similarity theory (Rushton, 1989; Rushton, Russell & Wells, 1984): more attracted to strangers who resemble you than who don’t more attracted to strangers who resemble you than who don’t leads to offspring with not only your genes but genes like themselves leads to offspring with not only your genes but genes like themselves Rushton’s research shows that people are more attracted to genetically similar people Rushton’s research shows that people are more attracted to genetically similar people People who go on to have children together are more alike than those who don’t. Thus among sexually active couples, those most genetically similar are those most likely to have reproduced. People who go on to have children together are more alike than those who don’t. Thus among sexually active couples, those most genetically similar are those most likely to have reproduced. Attraction not limited to the opposite sex. We tend to be friends with people who are genetically similar. Why? From an evolutionary perspective it’s because you are more likely to be altruistic to a friend than a stranger, making it more likely that the friend will go onto reproduce (similar genes to your own) and you may n\meet the friend’s opposite sex sibling - close genes again! Attraction not limited to the opposite sex. We tend to be friends with people who are genetically similar. Why? From an evolutionary perspective it’s because you are more likely to be altruistic to a friend than a stranger, making it more likely that the friend will go onto reproduce (similar genes to your own) and you may n\meet the friend’s opposite sex sibling - close genes again! How do we detect this genetic similarity: either drawn to those with similar facial and bodily features OR via smell. How do we detect this genetic similarity: either drawn to those with similar facial and bodily features OR via smell.

Please think of a serious committed relationship you have had in the past, that you currently have, or that you would like to have. Imagine that the person with whom you’ve become seriously involved became interested in someone else. What would distress or upset you more? –(a) Imagining your partner forming a deep emotional attachment to that person OR –(b) Imagining your partner enjoying passionate sexual intercourse with that person

Sexual/relationship jealousy Based on evolutionary forces, men and women approach sexual jealousy differently Buss, Larsen, Westen, and Semmelroth (1992) men and women were asked to respond to the previous vignette: FEMALES = 82% option (a) 18% option (b) MALES = 40% option (a); 60% option (b) Males jealous of sexual fidelity Females jealous of emotional fidelity

Brain function and personality 1. Behavioral approach system (BAS) IncentivesIncentives Left frontal lobeLeft frontal lobe dopaminedopamine 2. Behavioral inhibition system (BIS) withdrawalwithdrawal Right frontal lobeRight frontal lobe Serotonin?Serotonin? Anxiety/cues of threatAnxiety/cues of threat BAS and BIS act independently

Link to temperament 1. BIS sensitivity and emotional instability/neuroticism 2. BAS sensitivity related to extraversion 3. Role of impulsivity 4. Zuckerman – sensation seeking

Role of hormones Sex hormones important: weeks 8 – 24 prenatally, in months 1-5 after birth, and after puberty weeks 8 – 24 prenatally, in months 1-5 after birth, and after puberty changes to nervous system changes to nervous system Link to behavior in children Reinisch, 1981 sex difference effect of prenatal exposure filter by cognitions

Hormonal links to behavior in children continued Berenbaum & Hines (1992) 1.Androgen exposed girls played with boys’ toys 2.No difference in boys Jacklin, Maccoby, & Doering (1983) 1.Boldness or timidity of infant boys 2.No effect for girls

Testosterone and adult personality Testosterone and adult personality